text: /*	crypt() - one-way password encryption function	Author: Kees J. Bot
   *								7 Feb 1994
   * This routine does not encrypt anything, it uses the pwdauth
   * program to do the hard work.
   */
  #define nil ((void*)0)
  #define pipe _pipe
  #define fork _fork
  #define close _close
  #define dup2 _dup2
  #define execl _execl
  #define read _read
  #define _exit __exit
  #define write _write
  #define waitpid _waitpid
  #include <sys/types.h>
  #include <unistd.h>
  #include <string.h>
  #include <stdio.h>
  #include <errno.h>
  #include <stdarg.h>
  #include <sys/wait.h>
  
  /* Set-uid root program to read /etc/shadow or encrypt passwords. */
  static char PWDAUTH[] = "/usr/lib/pwdauth";
  #define LEN	1024
  
  static void tell(const char *s0, ...)
  {
  	va_list ap;
  	const char *s;
  
  	va_start(ap, s0);
  	s= s0;
  	while (s != nil) {
  		(void) write(2, s, strlen(s));
  		s= va_arg(ap, const char *);
  	}
  	va_end(ap);
  }
  
  char *crypt(const char *key, const char *salt)
  {
  	pid_t pid;
  	int status;
  	int pfd[2];
  	static char pwdata[LEN];
  	char *p= pwdata;
  	const char *k= key;
  	const char *s= salt;
  	int n;
  
  	/* Fill pwdata[] with the key and salt. */
  	while ((*p++ = *k++) != 0) if (p == pwdata+LEN-1) goto fail;
  	while ((*p++ = *s++) != 0) if (p == pwdata+LEN-0) goto fail;
  
  	if (pipe(pfd) < 0) goto fail;
  
  	/* Prefill the pipe. */
  	(void) write(pfd[1], pwdata, p - pwdata);
  
  	switch ((pid= fork())) {
  	case -1:
  		close(pfd[0]);
  		close(pfd[1]);
  		goto fail;
  	case 0:
  		/* Connect both input and output to the pipe. */
  		if (pfd[0] != 0) {
  			dup2(pfd[0], 0);
  			close(pfd[0]);
  		}
  		if (pfd[1] != 1) {
  			dup2(pfd[1], 1);
  			close(pfd[1]);
  		}
  
  		execl(PWDAUTH, PWDAUTH, (char *) nil);
  
  		tell("crypt(): ", PWDAUTH, ": ", strerror(errno), "\r\n",
  								(char *) nil);
  		/* No pwdauth?  Fail! */
  		(void) read(0, pwdata, LEN);
  		_exit(1);
  	}
  	close(pfd[1]);
  
  	status= -1;
  	while (waitpid(pid, &status, 0) == -1 && errno == EINTR) {}
  	if (status != 0) {
  		close(pfd[0]);
  		goto fail;
  	}
  
  	/* Read and return the result.  Check if it contains exactly one
  	 * string.
  	 */
  	n= read(pfd[0], pwdata, LEN);
  	close(pfd[0]);
  	if (n < 0) goto fail;
  	p = pwdata + n;
  	n = 0;
  	while (p > pwdata) if (*--p == 0) n++;
  	if (n != 1) goto fail;
  	return pwdata;
  
  fail:
  	pwdata[0] = salt[0] ^ 1;		/* make result != salt */
  	pwdata[1] = 0;
  	return pwdata;
  }
  
  /*
   * $PchId: crypt.c,v 1.5 1996/04/11 07:46:11 philip Exp $
   */
  